Interesting post. I shoot the K-Hornet, and have always worked on the assumption that it headspaces on the rim, just like the regular Hornet. I can't speak to the AI Hornet.
Check the Redding website, they might make dies for the Ackley Hornet. They won't be cheap.
Oh.. forgot. I fireform my brass using my standard load for the 40gr hp bullet I shoot as a fun load. Probably around 2500-2600 fps, IIRC. Accuracy is as good as with the fireformed brass, no need to worry there.
I always felt that if I got to the point where I thought it was time to bury my firearms, it was actually time to pick them up..